1. Field of the Invention
The present invention generally relates to a computer and chassis construction for electronic components and more particularly to a chassis construction for housing a computer for operation in severe environments.
2. Description of the Related Art
Hitherto the invention, conventional computer systems such as those incorporating the IEEE-1014 Standard Virtual Memory Extension (VME) bus have been predominantly used for embedded applications in severe environments, due to technology lags in personal computer (PC)-based systems. For the purposes of this application, a severe environment is defined as one subject to large environmental extremes due to temperature, humidity, radiation, electromagnetic induction, etc. An "embedded application" is defined as a specific function(s) which is contained within a larger application and requires no human intervention beyond supplying power to the computer. For example, embedded applications include, but are not limited to, systems and process control, communications, navigation, and surveillance.
However, the conventional VME-based systems are inefficient in cooling the internal computer components in that the systems are configured to have integrated circuit (e.g., "chips") mounted on one or more printed circuit boards, with the boards in turn being mounted on a wall of a sealed chassis by a coupling mechanism. The conventional systems used in severe environments rely on conduction cooling of the internal components. However; the thermal transfer path in such systems is relatively long and relies on a plurality (e.g., three) of interfaces between the chip and the chassis (e.g., the interface between the chip and the board, the interface between the board and the coupling mechanism and the interface between the coupling mechanism and the chassis wall) for cooling. Each of the three interfaces dissipates a portion of the heat being conducted along the thermal transfer path between the chip and the chassis wall. Hence, inefficient cooling of the conventional systems results from the heat dissipation at the interfaces, which may lead to faulty operation of the conventional systems.
Further, none of the conventional systems is PC-based. Another problem of the conventional systems is that, compared to a PC-based system, an inordinately large amount of resources are consumed in the conventional system's software development. A typical conventional system's application requires developing the application's source code on a host computer, such as a SUN or Digital Equipment Corporation (DEC) computer or the like, and then cross-compiling the host source code to the native instruction set of the target computer. Debugging must occur at both the host computer and the target computer. Once logical bugs are discovered and corrected in both the host computer and the target computer, then timing and input/output (I/O) bugs must also be detected and corrected. Such operations are particularly difficult when working with different computer architectures. Often other expensive electronic equipment, e.g., a central processing unit (CPU) emulator, must be coupled to the target CPU board to detect the more esoteric timing problems.
Moreover, VMEbus-embedded systems are inherently more costly, labor intensive, and time-consuming for the developer to generally field (in a severe or a friendly environment) than personal computer (PC)-based systems.
Notwithstanding the above problems, VMEbus-embedded systems have been predominantly used in the severe environment arena due to technology lags in the PC-based systems.
However, new computing technology has recently emerged which now makes the PC architecture more cost-effective for many embedded systems. This new technology includes: 1) increased availability of application code created for PC-compatibles; and 2) PC microprocessor advances. New higher density memory chips (including flash programmable read-only memories (PROMs)), highly integrated, low-cost interface chips, and the newer more powerful processors such as the Intel 80X86 processors, the Motorola 6800X0 family of processors, or the like, combine for an attractive hardware platform for massive and complex embedded applications.
Prior to the invention, no truly low cost, environmentally sealed and permanently mountable embedded computer was known which was reliably conduction-cooled.
Further, there is no known system that could leverage the installed software base of the IBM PC desktop computer system and yet be reliably used in a severe environment with efficient cooling by conduction. Known low cost, embedded, IBM PC compatible computers are either air cooled by internal fans or passive ventilation holes, or are partially sealed in a clipboard, laptop, or notebook type configuration. These latter types of configurations provide only limited sealing and thus are vulnerable to severe environments to include EMI (electromagnetic interference) environments. Further, the existing systems use card edge connections for card insertion which is a serious drawback in high vibration environments since breakage or slippage of the cards and the connectors is likely and further connections may be exposed to result in oxidation thereof, thereby decreasing the operational effectiveness of the known computers.
Thus, none of the known units is reliably conduction cooled and no known unit is a low cost, environmentally sealed and permanently mountable embedded computer which is able to leverage the installed software base of the IBM PC desktop computer system.
Further, hitherto the invention, no manufacturer has fit the array of components that is required to construct a conduction-cooled PC into the restricted dimensions and mounting requirements of the package known as an Air Transport Rack (ATR) Chassis and in accordance with standardized mounting form factors and mounting specifications as defined by the Aeronautical Radio Incorporated (ARINC) 404 and ARINC 600 form factors.